High frequency transistor

摘要

A high-frequency transistor is provided having a small effective emitter width and a low base bulk resistance. The transistor is isolated from adjacent components by insulating material portions. The base zone comprises first and second doped zones. The first zone establishes the effective emitter width and has a lower concentration than the second zone. The lateral extent of the first zone is established by one of the insulating material portions and the second zone of the base zone. The collector of the transistor is positioned beneath both the first and second zones of the base zone and the emitter of the transistor is positioned above the first zone and an end portion of the second zone.